There is sometimes an occasion that a screw equipped with a flat washer and a rubber washer is used for fixing a circuit board (refer to Japanese Patent Application Laid-Open Publication No. 2014-240675 as Patent Document 1, for example).
A hole in the flat washer is inserted through a shaft portion so as to be adjacent to a head portion of a screw body, and a hole in the rubber washer is inserted through the shaft portion as well.
The washer-equipped screw disclosed in Patent Document 1 pressed down a circuit board by an elastic force of the rubber washer.
A thermal deformation of the circuit board can also be absorbed by the elastic force of the rubber washer.
In the washer-equipped screw disclosed in Patent Document 1, a projection that contacts with the shaft portion of the screw body is formed on an inner peripheral surface of a hole of the rubber washer, so that the flat washer and the rubber washer do not detach.
However, the rubber washer may detach together with the flat washer with only the frictional force of the rubber washer against the shaft portion.
In addition, when it is assumed that the process of passing the flat washer through the shaft portion and further passing the rubber washer through the shaft portion is performed by a machine, there is a risk that the flat washer may detach before inserting the rubber washer.